DE1164397B - Process for the production of acrylic acid or methacrylic acid amide by amidating acrylic acid or methacrylic acid alkyl esters - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Class: C 07 c

German class: 12 ο - 21

Number: 1164 397

File number: R 25377IV b / 12 ο

Filing date: April 23, 1959

Opening day: March 5, 1964

For the preparation of acrylic and methacrylic acid amide several processes are known without one of these methods can be described as completely satisfactory. It is possible to do keto or Aldehyde cyanohydrins with concentrated sulfuric acid to the amide of an unsaturated carboxylic acid to implement, e.g. B. acetone cyanohydrin to methacrylic acid amide and ethylene cyanohydrin to acrylic acid amide. While the first-mentioned procedure is practiced as a technical procedure, the implementation has of ethylene cyanohydrin so far no technical significance. You can namely acrylic acid amide by the action of sulfuric acid and water on acrylonitrile, advantageously in a molar ratio of 1: 1: 1. The resulting reaction product. becomes alkaline with reactive compounds, e.g. B. with quick lime, calcium carbonate, ammonia or amines, decomposed and the free amide either by extraction with an organic solvent or by Sublimation won.

Further possibilities for the production of amides of unsaturated carboxylic acids, such as the decomposition of / KMethoxypropionsäureamiden at 200 to 300 ° C or the conversion of the chlorides unsaturated Carboxylic acids or esters of these acids with ammonia have been unsatisfactory because of the results so far found no practical application. During the aminolysis of carboxylic acid esters a well-known method for the preparation of amides of saturated carboxylic acids is that same procedure for the corresponding implementation of unsaturated carboxylic acid esters because of the very low Speed of implementation in the desired sense and technically only because of the addition of ammonia to the double bond difficult to do.

The action of aliphatic carboxamides on the esters of a, ^ -unsaturated carboxylic acids in the absence of catalysts is described in the monthly journals for chemistry, vol. 78, 1948, pp 129 to 138, but under the given conditions an addition to the Ethylenic double bond instead. Even when the processes of German patents 734725 and 735 771 were taken into account, it was not to be expected that the reaction of the acrylic acid amides with the unsaturated esters would take place as a substitution reaction in the presence of alkylic catalysts.

It has now been found that acrylic acid amide and methacrylic acid amide can be used in a simple manner and a process for the preparation of acrylic acid amide
or methacrylic acid amide by amidating
Acrylic or methacrylic acid alkyl esters

Applicant:

Rohm & Haas G. m. B. H.,

Darmstadt, Mainzer Str. 42

Named as inventor:

Dr. Nicolaus Jochum,

Dipl.-Chem. Kurt Riefstahl, Darmstadt,

Adolf Tilly, Berlin

in good yields by reacting acrylic or methacrylic acid alkyl esters in the alkyl radical Containing 1 to 4 carbon atoms, with straight-chain, saturated fatty acid amides, which have a free Amino group and contain 1 to 4 carbon atoms in the fatty acid residue, or mixtures thereof in Presence of a small amount of lithium hydroxide or magnesium methylate as a catalyst and in Presence of a stabilizing agent, preferably hydroquin, and optionally an inert one Solvent at the boiling point of the resulting saturated fatty acid ester, which is continuously is distilled off, can be produced.

In addition to formamide, the other suitable saturated acid amides are solid compounds at normal temperature. Acetamide and propionic acid amide melt at about 80 ° C., butyric acid amide at about 115 ° C. If the reaction is carried out at normal pressure, the reaction temperature corresponds approximately to the boiling point of the saturated ester formed. In most cases, the readily available, commercially available methyl and ethyl esters of acrylic and methacrylic acid are used as the starting point. If the reaction is carried out at normal pressure, it takes place around the boiling point of the acrylic or methacrylic acid ester used. For example, the reaction with the use of methyl acrylate at about 84 ° C and in the use of methyl methacrylate is conducted at about 100 ⁰ C. The amidation can also take place at higher temperatures, but then work must be carried out in a pressure vessel. It can, so that the reaction mixture is liquid,

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be appropriate in the presence of an inert solvent, e.g. B. a hydrocarbon, one Ketones or an alcohol to work with a sufficiently high boiling point. Albeit the use of the liquid formamide at the reaction temperature is possible in principle, one will because of the decomposition of this compound mostly with the amide of one of the higher molecular weight fatty acids realize.

Acrylic acid and methacrylic acid amide are very polymerizable compounds. So much for a solvent is used as a diluent in their preparation according to the invention, the polymerization of the monomer formed can optionally after the addition of a further polymerizable Compound the production of copolymers under the action of known accelerators take place directly in this solvent, it being due to the nature of the solvent and that of the resulting polymer or mixed polymer depends on whether a solution or a precipitation polymer arises. Leaving the reaction in the presence of excess starting ester as a diluent run, it is during or after the transamidation of the saturated one formed Carboxylic acid ester liberated the reaction product a polymerizable mixture of unsaturated ester and unsaturated carboxamide, which is converted into the corresponding copolymer in a manner known per se can be transferred. The monomeric amide can also by recrystallization or, as in the Acrylic acid amide can be obtained in pure form by sublimation.

In special cases it can be useful to carry out the transamidation with a mixture of several Carboxamides, e.g. B. with a mixture of formamide and acetamide or of acetamide and Propionic acid amide to perform. The melting point of one of e.g. B. Acetamide and propionamide existing As expected, the mixture is below 80.degree. C., so that it may also be used a diluent can be dispensed with.

For the economic viability of the procedure described, the possibility of the implementation saturated carboxylic acid ester formed according to the invention in a simple and known manner converting it back into the corresponding acid amide with ammonia is of crucial importance. This reaction is e.g. B. in Ulimann's Encyclopedia of Industrial Chemistry, Vol. 6, 1955, pp. 795 to 803, in Kirk-Othmer, Encyclopedia of Chemical Technology, Vol. 1, 1947, pp. 45, 47 ff., and in Houben-Weyl, Methods of Organic Chemistry, Bd. 8, 1952, pp. 658/659, described in detail, so that on the closer presentation of this known Procedure can be dispensed with. Although the production of acrylic acid and methacrylic acid amide according to the method of the invention with the inclusion of the restoration of the saturated acid amide, However, for which no protection is claimed, consists of two separate working methods The new procedure has proven to be progressive compared to the known processes.

Example 1 ₆

387 g (4.5 mol) of methyl acrylate are mixed with 180 g (3 mol) of acetamide with the addition of 0.5% Hydroquinone as a stabilizing agent and 2 g of magnesium methylate using a distillation column heated, thereby distilled at a head temperature of 57 to 60 ° C methyl acetate in the theoretically expected amount.

The contents of the flask are removed from excess methyl acrylate in vacuo at 100 to 200 mm of mercury freed. The residue crystallizes on cooling and is recrystallized from benzene; pure acrylic acid amide is obtained in a yield of 85% of theory.

Example 2

The same approach as in Example 1 does not remove excess in vacuo after the reaction has ended Acrylic acid methyl ester freed, but diluted with so much water that a 20% solution of acrylic acid amide in water and the excess methyl acrylate as the upper Layer can be peeled off. The amide contained in the aqueous solution can by known methods are polymerized. The yield is 92.5% of theory.

Example 3

450 g (4.5 mol) of methyl methacrylate are mixed with 135 g (3 mol) of formamide. After this Addition of 1 g of hydroquinone and 2 g of lithium hydroxide is added to the mixture while stirring Heated using a distillation column, as a result of which the methyl formate distills a head temperature of 35 to 40 ° C.

The residue is strongly cooled so that the methacrylic acid amide crystallizes out and is filtered off can be separated from the methyl methacrylate. The crystals are in the vacuum drying cabinet dried and then sublimed.

206 g of pure methacrylic acid amide are obtained, corresponding to a yield of 80% of theory. while the filtrate still contains 25 g of the amide and can be used again in the next attempt can.

Claims (1)

Claim: Process for the preparation of acrylic acid or methacrylic acid amide by amidating Acrylic acid or methacrylic acid alkyl esters, characterized in that acrylic acid or methacrylic acid alkyl esters, which contain 1 to 4 carbon atoms in the alkyl radical, with straight-chain saturated fatty acid amides, which have a free amino group and in the fatty acid residue Containing 1 to 4 carbon atoms, or mixtures thereof in the presence of a small amount Lithium hydroxide or magnesium methylate as a catalyst and in the presence of a stabilizing agent, preferably hydroquinone, and optionally an inert solvent at the boiling point of the resulting saturated Fatty acid ester converts, which is continuously distilled off. Considered publications: German Patent Specifications No. 734725, 735 771, 450,968 679; German Auslegeschrift No. 1 046 608; U.S. Patent Nos. 2,508,279, 2,615,918;